Driving Drops Again, but What’s the Big Picture?

December 12, 2011

USA Today always makes a point to cover national trends in transportation, and Larry Copeland and Paul Overberg’s piece last week is no exception. “Economy, gas prices make Americans drive less” is an excellent summary of the recent changes in vehicle miles traveled, or VMT.

The general story is this: Americans have sustained annualized driving drops for six consecutive months, the longest sustained drop since 2008. This also comes at a time when the country showed positive economic growth--2 percent annualized growth in the third quarter--and a string of positive, private sector job reports. These divergent trends reinforce the recent decoupling of VMT and economic growth. But does aggregate driving tell us the whole story about American driving habits?

We tend to think personal driving is a better indicator. And that metric reveals a leveling-off in the works for even longer (see chart at the bottom of this post). My colleague Rob Puentes and I first noticed these changes in VMT per capita--or a generalized measure of miles driven per person--back in 2008. Based on our updated calculations of national VMT and Census population estimates, VMT per capita in September 2011 is less than 9,500 miles.

The last time the country saw a VMT per capita rate that low-- September 1997.

Let’s put that date in perspective and the changes we’ve experienced since. The country’s economy grew by over 34 percent (inflation-adjusted). We added roughly 44 million people. Cell phone ownership rates jumped from near 20 percent to over 80 percent. The number one song in America was Notorious B.I.G.’s “Mo Money, Mo Problems.” So not everything improved, but you get my drift.

If the nation’s grown in so many respects, especially in economic production, how can personal driving have just stalled-out (pardon the pun)? Researchers think there’s quite a few reasons--slowing demographic shifts, like women entering the workforce; rising levels of ecommerce; sustained jumps in real gas prices--but another alternative is that younger generations simply aren’t driving as much as their forbearers. Is that just a change in the economic climate, or does the upcoming generation really value driving less? We’ll have to wait and see if they sustain these attitudes as more enter the workforce.

Another theory is that households, and commuters in particular, are switching some trips from personal automobile to public transit. On the same day as the U.S. Department of Transportation announced the drop in driving, updated public transportation statistics showed ridership increases, just as we found in our State of Metropolitan America report.

Is this another sign of changing attitudes in American transportation? Is more multi-modality in our future?